The camaraderie between Stuart Armstrong and Gary Mackay-Steven was never going to be blunted by the latter’s move from Celtic to Aberdeen in the summer. It will, though, be rendered nonexistent as the result of Mackay-Steven facing up to his friend while adorned in red tomorrow, in what will be the winger’s first appearance at Parkhead since he left the club four months ago.

Armstrong would have been able to swap goalscoring boasts with his old mucker after the Celtic midfielder scored a corker against Partick Thistle the other night to counter the hat-trick the Aberdeen wide-man bagged in the 4-0 whipping of Hibernian last weekend. “I saw him the other day and he wouldn’t stop talking about his hat-trick!” the 25-year-old Scotland international said. “As long as he doesn’t do that again on Saturday we will be fine.”

What Armstrong won’t feel able to do is swap pleasantries when he faces up to Mackay-Steven on a football field for the first time, almost six years after they became firm friends when the winger signed for Dundee United in the summer of 2011.

“I won’t even look at him,” Armstrong said. “Everyone’s different – sometimes people see mates on the pitch and make a few jokes with them, that is just not me. I like to focus on the game. When I first came here [to Celtic in January 2015], we played Dundee United straightaway and I didn’t say a word to anybody.

“It’s funny, I just saw [former United colleague] Blair Spittal downstairs after the Thistle game and he was making jokes about me, saying I ignored him for 90 minutes. That is just how I am – I don’t like to speak to any friends – I just like to concentrate on the game and after I can speak to them or have a joke with them.”

With his hat-trick, Armstrong believes that Mackay-Steven has shown “what a threatening player he can be” on his day, with those days glimpsed just too infrequently in a frustrating stint at Celtic. Armstrong can put club rivalries to one side when assessing his pal’s return to the football spotlight.

“He’s one of my closest friends so when somebody you know does well you’re always happy for them,” he said. “I was really pleased to see him score three and fulfil his potential like that. He is a quality player – I have played with him for five years or so and seen his qualities day in day out in training. Sometimes things just don’t work out in certain places but he is definitely showing his quality again at Aberdeen.”

The encounter itself is a potentially pivotal one in the title race. A victory for Brendan Rodgers’ men would send them eight points clear at the summit of the Premiership. If the Pittodrie side were to become the first Scottish side in two years to register an away win at Celtic Park, Derek McInnes’ men would move to within two points of the defending champions.

“[It’s a huge game], especially with the winter break coming,” said Armstrong. “They’ll be wanting to get as close as possible. For us, it’s about stretching that gap at the top. That’s our aim to get to the winter break with a big gap, then we hope to stay up there.”

Armstrong believes Celtic showed their “strength” and “character” in bouncing back with a 2-0 success over Thistle following the 4-0 thumping away to Hearts that ended their 69-game sequence without a domestic defeat. He maintains that the end of their remarkable 19-month run was never going to sink their mood. “It was bound to happen eventually,” he said. “It wasn’t the way we would have liked. I don’t think we were feeling sorry for ourselves, it was a disappointing performance but it was still an incredible achievement to reach that record. To come back and win again against Thistle… only 69 to go to get a new one.”

It might feel that Celtic could play these in the space of a season, owing to their packed schedule from the mid-July start of the Champions League qualifying campaign. Already, Rodgers’ side have contested 35 competitive matches and Armstrong does not deny that such relentlessness can affect performances levels. Those have dropped off significantly in recent months and, aside from the 3-0 cuffing of Aberdeen at Pittodrie two months ago, there have been few commanding displays of the type they regularly produced in claiming an unprecedented unbeaten treble last season.

“We had a busy season last season and a short summer break. It has really been a full year of football,” he said. “We have a big squad but a lot of boys have put a lot into every single match and there’s about nine in December in total. That plays a part. But the energy is there – and the belief.”